This invention relates generally to a rotary valve position sensor, and more particularly to an electrical or electronic sensor which indicates the position of a valve.
Typical control systems for capacity control valves on rotary screw compressors consists of pneumatic, hydraulic, and electrical components. These systems are often complicated, expensive and require frequent service. Recently, stepper motors have been used for this purpose. Although the use of stepper motors reduces the number of moving parts and associated wear problems, stepper motors require feedback of inlet valve position. Furthermore, the electronics required for this feedback must be protected from damage or contamination in industrial environments.
Examples of electronic control for inlet valves include encoders, which have been placed on the output end of the stepper motors to sense the position of the valve. The encoders determined the position of the valve by determining the number of impulses input to the stepper motor to cause angular displacement. There was no assurance that the position of the valve was accurately reflected by the position of the stepper motor.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.